Fluid detection apparatuses detect the presence and absence of fluid. Fluid detection apparatuses have been used in printing systems such as printing systems having replaceable ink cartridges. For example, fluid detection apparatuses can detect when the respective ink cartridge has a low ink level and, thus, a user can be notified. Therefore, the user can be provided with an opportunity to change the replaceable ink cartridge and prevent the printing system from running out of ink during a print job.